FXUS63 KDVN 090934
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
334 AM CST WED DEC 9 2009
.SYNOPSIS...
AT 2 AM...RAPIDLY DEEPENING SURFACE LOW LOCATED JUST SE OF MOLINE
WITH SURFACE PRESSURE OF 982 MB. SYSTEM DEEPENING 1+ MB PER HOUR
WITH STRONG PRESSURE RISE/FALL COUPLET TO PASS OVER FORECAST NEXT
6 HOURS FOR MAX WINDS NEXT 8-12+ HOURS SUPPORTING BLIZZARD AND NEAR
BLIZZARD CONDITIONS UNTIL LATE PM AND POSSIBLY INTO EARLY EVENING.
ISOLATED THUNDER-SNOW WITH DEFORMATION ZONE APPEARS TO BE ENDING
WITH AREA SNOWFALL TOTALS OF 8-12+ INCHES NORTH OF A STERLING TO
DEWITT TO WASHINGTON LINE. LOWER AMOUNTS OF 3 TO 7 INCHES APPEAR
WILL OCCUR SOUTH OF THIS LINE WITH SOME ICE ACCUMULATIONS FROM THE
EARLIER FREEZING RAIN AND SLEET. ]
&&
.SHORT TERM...TODAY AND TONIGHT...
LITTLE CHANGES MADE TO CURRENT FORECAST. HIGH SUSTAINED WINDS OF
30 TO 40 MPH WITH GUSTS TO 50+ MPH TO ARRIVE BY DAYBREAK OVER MOST
OF THE AREA. CURRENT BLIZZARD WATCH SHOULD VERIFY WITH PERIODS OF
VERY LOW VISIBILITIES AND NEAR WHITEOUT CONDITIONS...MOST NOTABLY
ALONG AND NORTH OF HIGHWAY 30. CONDITIONS SHOULD START TO SLOWLY
IMPROVE BETWEEN 4 PM AND 8 PM AS DAYTIME HEATING ENDS LIMITING THE
AMOUNT OF NON-ADIABATIC LOW LEVEL MIXING. ADDITIONAL SNOW AMOUNTS
TODAY SHOULD BE MAINLY AN INCH OR LESS BUT WILL BE HARD TO KNOW
DUE TO THE WIDESPREAD BLOWING SNOW. LOCAL TECHNIQUES STILL SUGGEST
ISOLATE MAX GUSTS NEAR 60 POSSIBLE THAT WOULD ENHANCE RISK OF
POWER OUTAGES AND FALLEN TREE LIMBS AND ENTIRE TREES. TEMPERATURES
WILL FALL THE ENTIRE DAY INTO THE SINGLE DIGITS BY DUSK WITH WIND
CHILLS BELOW ZERO. THE MOST RAPID FALL IN TEMPERATURES WILL OCCUR
EARLY TO MID MORNING. MOST OF THE SNOW IS WET...WHICH SHOULD LIMIT
DRIFTING OF SNOW TO HOPEFULLY A DEPTH OF 3 TO LOCALLY UP TO 6 FEET.
TONIGHT...KEPT WINDS 15 TO 20 MPH WITH SOME GUSTS OVER 25 MPH IN
THE EVENING HOURS WHICH SHOULD ALLOW FOR DECREASING BLOWING SNOW.
TRENDS SUGGEST THE FAR NORTH SECTIONS MAY BE ABLE TO BE TRIMMED TO
EXPIRE THE BLIZZARD WARNING ABOUT 03Z FOR DAY SHIFT TO DECIDE.
SKIES SHOULD CLEAR AND LOWS WITH DEEP SNOW COVER OF 6+ INCHES
SUGGEST SHOULD SEE 5 TO 10 BELOW ZERO WITH WIND CHILLS AOB 20
BELOW ZERO. THIS LIKELY WILL REQUIRE A WIND CHILL ADVISORY BE
ISSUED LATER TODAY FOR THE EXTREME COLD. ..NICHOLS..
.LONG TERM...THURSDAY THROUGH NEXT TUESDAY...
ARCTIC AIR BEING PULLED DOWN BEHIND THE DEPARTING STORM WILL RESULT
IN QUIET BUT COLD CONDITIONS THURSDAY. BASED ON PROJECTED MAX
TEMPERATURES AND WINDS...SOME TYPE OF HEADLINE WILL BE NEEDED
THURSDAY MORNING BECAUSE OF THE COLD.
QUIET AND COLD CONDITIONS ARE EXPECTED THURSDAY NIGHT AND FRIDAY AS
THE ARCTIC HIGH MOVES ACROSS THE AREA. AS RETURN FLOW DEVELOPS
FRIDAY NIGHT INTO SATURDAY...LOW LEVEL WAA SHOULD RESULT IN AN
INCREASE OF CLOUD COVER...ESPECIALLY FROM THE DEEPER SNOW FIELD ON
NORTH. WAA AND CLOUD COVER WILL HELP TEMPERATURES MODERATE AND BE
CLOSER TO NORMAL.
SATURDAY NIGHT ON...NO CHANGES WERE MADE TO THE CURRENT FCST.
HOWEVER...THE GLOBAL MODELS CONTINUE WAA SATURDAY NIGHT INTO SUNDAY
AND START BREAKING OUT VERY LIGHT PRECIPITATION. IF SO...THERE WOULD
BE A POTENTIAL FOR SOME -SN/FZDZ...ESPECIALLY OVER THE SNOW FIELD.
GLOBAL MODELS ALSO SUGGEST A SYSTEM MOVING THROUGH THE AREA SUNDAY
NIGHT INTO MONDAY. BOTH THE ECMWF/GEM DIFFER ON DETAILS BUT THE
ECMWF IS MORE BULLISH WITH PRECIPITATION. MODEL SOLUTIONS ARE HIGHLY
SMOOTHED BUT DO HINT AT A RESPECTABLE SHORTWAVE EMBEDDED IN THE
FLOW. CURRENT FCST HAS SCHC POPS WHICH SEEM REASONABLE THIS FAR OUT.
..08..
&&
.AVIATION...
IFR TO LIFR CONDITIONS THROUGH 19Z DUE TO LIGHT SNOW AND BLOWING
SNOW WITH VSBYS AOB 1 MILES WITH EXTENDED PERIODS OF 1/2 MILE OR
LESS DUE TO BLOWING SNOW AT DBQ AND CID TERMINALS. NW WINDS OF 25
TO 40 KTS TO RESULT IN EXTREME LOW LEVEL TURBULENCE DUE TO RAPID
OVERTURNING OF COLD AIR. AT BRL AND MLI TERMINALS...SHOULD
TRANSITION TO MVFR BETWEEN 19Z AND 01Z WITH BLOWING SNOW MAIN
ISSUE. CLOUD BASES TO STAY BELOW 1,000 FEET ALL TERMINALS UNTIL
AFTER 18Z AND THEN 1-3K AGL UNTIL SKIES CLEAR BETWEEN 02 AND 08Z.
VSBYS SHOULD BECOME AOA 7 MILES BY 08Z. ..NICHOLS..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...BLIZZARD WARNING UNTIL MIDNIGHT CST TONIGHT FOR BENTON-BUCHANAN-
CLINTON-DELAWARE-DUBUQUE-JACKSON-JONES-LINN.
BLIZZARD WARNING UNTIL 6 PM CST THIS EVENING FOR CEDAR-DES
MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-KEOKUK-LEE-LOUISA-
MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...BLIZZARD WARNING UNTIL MIDNIGHT CST TONIGHT FOR CARROLL-JO
DAVIESS-STEPHENSON.
BLIZZARD WARNING UNTIL 6 PM CST THIS EVENING FOR ROCK ISLAND.
WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR BUREAU-
HANCOCK-HENDERSON-HENRY IL-MCDONOUGH-MERCER-PUTNAM-WARREN-
WHITESIDE.
MO...BLIZZARD WARNING UNTIL 6 PM CST THIS EVENING FOR CLARK-SCOTLAND.
&&
$$
NICHOKLS/08
